Heretofore, pistons have been constructed primarily as die castings or from multiple piece stampings and wherein the multiple parts are assembled and welded. Heretofore, pistons have been made of assembled multiple parts and wherein outer annular portions have been machined to define an outwardly opening annular seal receiving groove.
The difficulty with pistons of the prior art of this type are that die cast pistons are of relatively high cost and often include porousity problems. In the manufacture of multiple part pistons, there is excessive time consumption in the accurate assembling of the respective parts and securing them together by welding or otherwise.